The present invention relates to wide mouth blow-molded plastic containers, and more particularly, the present invention relates to a preform and method for use in efficiently manufacturing multi-layer wide mouth blow-molded plastic jars suitable for hot-fill applications.
In the manufacture of blow-molded plastic bottles for containing liquids, such as beverages, it is customary to utilize an injection-molded preform having an injection molded threaded finish which ultimately forms the threaded finish of the container blown from the preform. The preform may be injection molded from a variety of desirable plastic materials, such as polyethylene terephythalate (PET), and may include an encapsulated gas barrier layer, such as an ethylene vinyl alcohol copolymer (EVOH) which is highly impermeable to oxygen when dry. Examples of multi-layer containers and preforms are disclosed in U.S. Pat. No. 4,526,821 issued to McHenry et al.; U.S. Pat. No. 4,535,901 issued to Okudaira et al.; U.S. Pat. No. 4,728,549 issued to Shimizu et al.; and U.S. Pat. No. 4,550,043 issued to Beck.
Some containers, particularly those molded of PET, have been utilized in hot fill applications where the blown container is filled with a beverage heated to a temperature in excess of 180xc2x0 F. (82xc2x0 C.), capped immediately after filling, and allowed to cool to ambient temperatures. In such containers, vacuum absorption panels are typically provided in the body of the container to accommodate vacuum induced shrinkage resulting from cooling of the container contents. In such containers, the injection molded threaded finish undergoes a minimal amount of distortion during the hot fill process. An example of a hot-fillable, multi-layer container having an injection molded finish is provided by U.S. Pat. No. 4,818,575 issued to Hirata et al.
For quite some time, there has been a need in the marketplace for a so-called wide-mouth container for hot-fill applications. A wide mouth container enables the consumer to scoop-out viscous contents which are not readily flowable. Such examples of viscous products include applesauce, spaghetti sauce, relish, pickles, beets, baby foods, sauerkraut, jelly, mayonnaise, and salad dressings to name a few. Examples of wide-mouth plastic containers are disclosed in U.S. Pat. No.: 5,092,474 issued to Leigner; U.S. Pat. No. 5,261,544 issued to Weaver, Jr.; Pat. No. D.423,936 issued to Smith et al.; Pat. No. D.420,593 issued to Denner et al.; and Pat. No. D.402,563 issued to Prevot et al.
In the early 1980""s, attempts were made to produce hot-fillable PET containers having blown wide mouth finishes. To this end, a preform with an injection molded finish was blow-molded to form an intermediate-article which included a blown container and a moil portion integrally extending from the blown threaded finish portion of the blown container. The injection molded finish is part of the moil portion which is severed from the intermediate article thereby leaving a finished wide-mouth container having a blown finish with external threads. This manufacturing technique and the resulting containers are disclosed in U.S. Pat. No.: 4,665,682 issued to Kerins et al.; U.S. Pat. No. 4,618,515 issued to Collette et al.; and U.S. Pat. Nos. 4,576,843 and 4,496,064 issued to Beck et al. The above referenced Kerins patent also discloses the use of a five layer wall structure consisting of three layers of PET and two encapsulated layers of a barrier material, SARAN.
There is a current need for a novel and improved hot-fillable wide mouth container which includes an embedded gas barrier layer and which is particularly suited for packaging viscous food products.
With the foregoing in mind, a primary object of the present invention is to provide a commercially satisfactory wide-mouth blow-molded container that has a multi-layer construction.
Another object of the present invention is to provide a preform and method which can be used to manufacture a multi-layer wide-mouth blow-molded plastic container and which form an intermediate article having a moil portion consisting essentially of a primary container material so that, after the moil portion is severed from the container, the moil portion can be readily and efficiently recycled.
Still another object of the present invention is to provide a multi-layer wide mouth blow-molded plastic container which has a blown finish that at least partially includes an encapsulated layer of a secondary material and that resists distortion resulting from hot-filling.
A further object of the present invention is to provide a method of manufacturing a multi-layer wide-mouth container which enables commercially acceptable hot fillable wide-mouth plastic containers to be produced by means of high speed manufacturing equipment in an economical manner that ensures consistent quality and performance.
More specifically, according to one aspect of the present invention, a method of making a multi-layer blow-molded plastic container having an externally-threaded wide-mouth finish for receiving a removable closure is provided. To this end, a tubular preform is provided having a container body forming portion, a moil forming portion and a blown finish forming portion. The container body forming portion includes a closed bottom end of the preform and has a multi-layer structure including at least one layer of a secondary material located between inner and outer layers of a primary container material. The moil forming portion includes an open top end of the preform and has a mono-layer structure consisting essentially of the primary container material so that it can be readily recycled. The blown finish forming portion is located between the container body forming portion and the moil forming portion. Preferably, the secondary material extends into the blown finish forming portion of the preform and terminates therein without extending into the moil forming portion of the preform.
The above referenced preform is preheated and then disposed into a mold cavity having a surface with a container body forming region, a blown finish forming region superadjacent the body forming region, and a moil forming region superadjacent the blown finish forming region. The preform is then distended against the surface of the mold cavity to form an intermediate container article including a multi-layer blow-molded plastic container having a blown externally-threaded wide-mouth finish and a moil extending upwardly from the blown finish. The moil is severed from the intermediate container article and is recycled post-manufacture but pre-consumer.
According to other aspects of the invention, a preform is provided having the above described structure and a multi-layer wide-mouth container is produced according to the above referenced process.